Four-lamp explosion-proof fluorescent fixtures presently in common use have four transparent glass sleeves, each of which surrounds one fluorescent lamp. Each sleeve is conventionally flared at both ends, and rests against a shoulder integral with a wall of an end housing at each end of the fixture. This sleeve is cemented into an aperture inboard of the shoulder in the long dimension of the fixture, while the unconnected end housings are held in a jig or fixture, and a ballast housing is fastened to and between the two end housings after the sleeves have been cemented. Although such conventional fixtures can be relamped through the open ends of the sleeves, if one of the sleeves must be replaced, all of the sleeves have to be broken. The conventional explosion-proof fluorescent fixtures use a standard forty-eight inch tube, which makes the lamp fixtures about fifty-two inches overall in length.
This problem was addressed in co-assigned U.S. Pat. No. 4,841,418 to Davis. Davis included openings in end housings through which the sleeve can pass. The sleeve, however, was cemented to the end housing. The fixture disclosed therein allowed for replacing individual sleeves without breaking all the sleeves. However, to do so required chipping out the cement. This is a time-consuming procedure. Further, it risks accidental breaking of a sleeve while chipping out cement.
One of the objects of this invention is to provide an explosion-proof fluorescent fixture in which the lamp tubes may be easily replaced.
Another object is to provide such a fixture wherein ballast may be removed and replaced without disassembling the ballast housing.
Another object is to provide such a fixture wherein an explosion proof integrity is maintained when lamp tubes and ballasts are removed and replaced.
These and other objects will become apparent to those skilled in the art in light of the following disclosure and accompanying drawings.